Comparison of Resting Magnetocardiography With Stress Single Photon Emission Computed Tomography in Patients With Stable and Unstable Angina

Background: Early diagnosis of ischemia is complicated by the poor sensitivity of standard tests (ECG and troponin) and contraindication for stress testing in unstable angina patients. Magnetocardiographic (MCG) imaging is a new technology developed for the rapid, non-invasive, non-stress detection of ventricular repolarization abnormalities at rest. Methods: 51 acute coronary syndrome patients from the telemetry unit and 33 normal controls were studied utilizing a 9-channel CMI Magnetocardiograph in unshielded location in the cardiac noninvasive laboratory. Scan time was 6 minutes and results were available immediately. The MCG data were processed and interpreted utilizing an automated MCG analysis program. All patients were chest pain free at the time of scanning. Results: The mean age was 60.2 ± 14.4 years (range 32 – 86) and 68.6% were men. Most had normal ECG (74.5%) and normal troponin I (83.3%). Ischemia determined by positive troponin I, positive imaging stress testing, and/or positive coronary angiogram (70% occlusion) were demonstrated in 54.9%. The MCG detected ischemia with high accuracy (p<0.0001) and high diagnostic value: Sensitivity 89.3%, specificity 85.7%, positive and negative predictive value of 75.8% and 94.1%, respectively. In the subgroup with negative troponin I and ECG, the sensitivity, specificity, positive and negative predictive values were 84.6%, 92.2%, 73.3%, and 95.9%, respectively. Conclusion: Resting magnetocardiographic imaging is a rapid no risk scan for the early and accurate detection of ischemia in a high risk patient population.